Correct Answer: C

Rationale: The correct answer is C: hypernatremia. Hypernatremia refers to an elevated level of sodium in the blood, specifically when it is more than 145 mEq/L. Choice A, hyponatremia, is incorrect as it refers to low sodium levels. Choice B, hyperkalemia, is incorrect as it refers to high potassium levels, not sodium. Choice D, hypercalcemia, is also incorrect as it relates to elevated calcium levels, not sodium.

Correct Answer: D

Rationale: The correct answer is D. Electrolytes are substances that dissociate into ions when dissolved in water, allowing the solution to conduct electricity. Choice A is incorrect because glucose does not form electrolytes when added to water. Choice B is incorrect as it states that electrolytes dissociate but do not form ions, which is inaccurate as electrolytes do form ions in water solutions. Choice C is also incorrect as it states that electrolytes form ions but may not necessarily dissociate, which goes against the definition of electrolytes that must dissociate into ions for conductivity. Therefore, choice D is the most accurate as it correctly describes that electrolytes dissociate in water solutions and form ions, highlighting the essential characteristics of electrolytes.

Correct Answer: D

Rationale: When a patient exhibits signs and symptoms of third-spacing, where fluid moves out of the intravascular space but not into the intracellular space, hypovolemia is expected. This leads to a decreased circulating blood volume. Increased calcium and magnesium levels are not typically associated with third-spacing fluid shift. Burns usually result in acidosis rather than alkalosis, making metabolic alkalosis an incorrect choice. Therefore, hypovolemia is the correct answer in this scenario.

Correct Answer: C

Rationale: The correct answer is C: 'plasma and interstitial fluid.' Extracellular fluid consists of all body fluids outside the cells, primarily including plasma (the liquid component of blood) and interstitial fluid (the fluid between cells). Choices A, B, and D are incorrect because intracellular fluid is located within the cells, not in the extracellular fluid compartment.

Correct Answer: D

Rationale: Intracellular fluid contains phosphate ions and protein molecules as essential anions. Phosphate ions play a crucial role in various cellular processes, including energy transfer. Proteins, being large molecules with negative charges, also contribute significantly to the negative ion concentration within cells. Chlorine is primarily an extracellular anion and is not as prominent as phosphate ions and proteins within intracellular fluid, making it a less important negative ion in this context. Therefore, the correct answer is D because both phosphate ions and protein molecules are crucial negative ions in intracellular fluid.